Bake until filling is set, about 40 minutes. Transfer to a wire rack, and let cool at least 30 minutes.

Set a heatproof bowl, or the top of a double boiler, over a pan of barely simmering water. Melt chocolate in bowl, stirring occasionally; remove from heat. Dip a spoon in melted chocolate, then drizzle chocolate over tart, forming decorative stripes. Refrigerate until well set, at least 1 hour and up to 1 day.